Biomedical subjects

G Gantt

Publications and source records attributed to G Gantt.

11 recordsLinked to original sources

PubMed1990

Rapid isolation of genomic DNA from animal tissues.

A simple technique for the isolation of very high molecular weight genomic DNA from animal tissues and cells is described. The method involves rapid isolation of nuclei and their embedding in agarose beads followed by extraction of lipids and proteins with SDS. The protocol does not require proteolytic digestion and the whole procedure can be completed in 1 day. The isolated DNA is digestible by restriction enzymes and free of ligase inhibitors.

Animals↗

PubMed1990

Cutaneous squamous cell carcinoma characteristics.

The second most common type of skin cancer, squamous cell carcinoma, carries a higher mortality rate than basal cell carcinoma. This article discusses the incidence, risk, characteristics, and prevention of the disease.

Carcinoma, Squamous Cell↗

PubMed1989

Etretinate. Persistent serum levels after long-term therapy.

In 47 patients who received long-term etretinate therapy, we measured serum etretinate concentrations from one to 244 weeks after the discontinuation of therapy. The earliest posttreatment, nondetectable serum concentration of etretinate was observed at five weeks after treatment. Detectable serum concentrations (0.05 to 1.2 micrograms/dL) were observed more than two years (108, 111, 131, 136, and 150 weeks) following the discontinuation of therapy. Sequential serum concentrations obtained on eight individual patients were used to determine half-lives for this late-phase elimination. The median half-life for the 12 curves obtained was 12.5 weeks (range, 5.3 to 24.8 weeks). Since etretinate is stored in fat, we compared each patient's deviation from ideal body weight as a measure of excess body fat with various pharmacokinetic factors of etretinate elimination. Overweight patients tended to have slower elimination, maintain higher serum concentrations, and clear etretinate later.

Adipose Tissue↗

PubMed1988

Expression of myelin protein genes in quaking mouse brain.

The expression of myelin proteins in actively myelinating quaking and control brains was studied. RNA was extracted from the brains of 18- and 27-day-old mice and analyzed by northern blot using cDNA probes for proteolipid protein (PLP), basic protein (BP), and myelin-associated glycoprotein (MAG). Two PLP transcripts of 3.2 and 2.4 kb (kilobase) were found, whereas PB and MAG probes hybridized to single regions of 2.2 and 2.5 kb, respectively. No abnormality in the transcript pattern was detectable in the quaking brain at either 18 or 27 days of age. Over this 9-day period the level of PLP and BP message in the control brain decreased by approximately 10%, whereas the level of MAG message decreased by approximately 50%. In the 18-day-old quaking brain the expression of PLP and BP was severely reduced amounting to one-third and one-half of the control values, respectively. The reduction at the age of 27 days was less. On the other hand, the quaking brain produced more MAG mRNA amounting to 1.6- and 3.2-fold control on the 18th and 27th day. The results indicate a reduced expression of the PLP and BP genes and a developmental delay in the mutant, whereas the genetic expression of MAG is enhanced and appears to be progressively dysregulated.

Aging↗

PubMed1987

Distribution of calcium-activated neutral proteinase activity in quaking mouse brain: a subcellular study.

The distribution of calcium-activated neutral proteinase (CANP) activity was examined in the subcellular fractions of quaking and control mouse brain. The CANP activity was determined in purified myelin, cytosol and pellet (P2, consisting of nuclei, mitochondria and microsomes) fractions using [14C]azocasein as substrate. The enzyme activity in quaking brain was 1.3-fold greater than control. Fifty-seven percent of the control brain activity was in purified myelin compared to only 7% in quaking myelin. The specific activity of the control purified myelin was 4-fold greater than homogenate while that of the quaking was two-fold greater. In contrast, 51% of the quaking brain activity was present in cytosol compared to only 18% in the control. Triton X-100 greatly increased the control brain activity (10-fold) while the quaking brain activity was increased by only 1.2-fold. The total calcium content in the quaking brain was greatly elevated (6-fold) compared to control. Approximately 30% of the brain 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) activity was in quaking myelin while 77% of the CNPase activity in control brain was in myelin. These results suggest that in quaking brain much of the CANP is not incorporated into the myelin membrane and remains cytosolic.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗

PubMed1987

Increased turnover of myelin proteolipid protein in quaking mouse brain.

Homozygous quaking and normal control littermate mice were injected intracerebrally with [3H]leucine at 19 days of age. The animals were sacrificed after 1 h and after 6 days. The proteolipid protein (PLP) and intermediate protein (IP) were extracted from whole brain by chloroform-methanol (2:1) and resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). One hour postinjection the labeling of total protein in quaking brain was the same as the control and the radioactivity of PLP and IP in quaking was approximately 35% of the control. Six days after precursor administration the radioactivity of the total protein decreased significantly in both groups and to the same extent. However, the labeling of PLP and IP more than doubled in the control, while it decreased by half in the quaking brain. The results indicate that there is an increased turnover rate of PLP and IP in quaking brain.

Animals↗

PubMed1986

Synthesis and acylation of myelin proteolipid protein in quaking mouse brain.

The synthesis and acylation of proteolipid proteins where investigated in tissue slices prepared from 19-day-old quaking and normal littermate mouse brain. The mutant CNS had a normal rate of total protein synthesis but synthesis of the myelin-specific proteins, proteolipid protein (PLP) and intermediate protein (IP), was impaired to approximately 50% of control. The acylation of myelin proteins with labeled palmitate was reduced to only about 20% of control. The acylation of two nonmyelin proteolipid proteins was also significantly reduced. The incorporation of palmitate into phospholipids was identical in control and mutant. The results indicate impaired synthesis of PLP and IP and a general deficit in protein acylation in quaking brain.

Acylation↗

PubMed1986

Peroxidative aggregation of myelin membrane proteins.

The exposure of CNS myelin to reactive oxygen species (ROS) generated by a Cu2+-H2O2 system results in the aggregation of membrane proteins. Integral and peripheral membrane proteins are equally vulnerable and the denaturation is not mediated by the SH groups. The aggregated proteins retain their original antigenicity as determined by immunoblot technique. The aggregation of proteins is not limited to myelin and can be elicited in the preparation of other cerebral membranes. The effect of ROS on membrane proteins can also be demonstrated in cerebral slices incubated in the presence of the ROS-generating system. Furthermore, the peroxidation inactivates membrane-bound enzymes as exemplified by myelin cyclic nucleotide phosphatase (CNP). Competitive inhibition studies with various scavengers and quenchers of ROS implicate singlet oxygen as a major mediator in the Cu2+-H2O2 oxidizing system responsible for the peroxidative aggregation of membrane proteins.

Animals↗

PubMed1984

Etretinate: effect of milk intake on absorption.

Since etretinate, an aromatic retinoid useful in the treatment of psoriasis and other skin disorders is lipid-soluble, it may be poorly absorbed in the absence of a fat load. We therefore studied serum concentrations of etretinate and its major metabolite (Ro 10-1670) after the controlled administration of etretinate. After an overnight fast, 6 Darier's disease and 4 psoriatic patients received a 1 mg/kg morning dose of etretinate with water or 1 pint of whole milk (fat load). There was a 260% increase (p less than 0.0005) in the mean of each patient's increase in the baseline-corrected peak serum concentration of etretinate after administration with milk (115 +/- 15 micrograms/dl) compared to after administration with water (32 +/- 4 micrograms/dl). Over a 24-h period there was an overall 296 +/- 26% (p less than 0.0005) increase in serum etretinate after administration with milk compared to water in 5 patients with Darier's disease. In contrast to the serum etretinate, there was a 17% mean decrease (p less than 0.025) in the corrected peak serum concentration of Ro 10-1670 in all 10 patients after administration of etretinate with milk compared to water. The net result of these alterations is that the mean corrected serum concentration of etretinate is higher than Ro 10-1670 at all time points measured after milk administration. In contrast, after administration of etretinate with water the major retinoid in the serum is Ro 10-1670. Establishing the clinical significance of these alterations may require controlled clinical trials.

Acitretin↗

PubMed1982

Basic proteins of rodent peripheral nerve myelin: immunochemical identification of the 21.5K, 18.5K, 17K, 14K, and P2 proteins.

Proteins in peripheral nervous system and central nervous system myelin and homogenates of sciatic nerve and brain from young and adult mice and rats were characterized with affinity-purified anti-P2 and anti-myelin basic protein sera after electrophoretic transfer from sodium dodecyl sulfate-polyacrylamide gels to nitrocellulose sheets. Using this method we have identified a component of rodent peripheral nervous system myelin as P2 protein. Peripheral nervous system myelin also showed the presence of four basic proteins in addition to P2 protein. These were found to be analogous to the 14, 17, 18.5, and 21.5K species found in the central nervous system myelin. A number of high-molecular-weight proteins were also detected with anti-myelin basic protein serum in peripheral nervous system, as well as central nervous system myelin. In addition, we report the presence of a high-molecular-weight P2 cross-reactive protein in rodent brain stem homogenates, but not in central nervous system myelin. Key Words: Basic proteins--PNS myelin--CNS myelin--Immunocharacterization. Greenfield S. et al. Basic proteins of rodent peripheral nerve myelin: Immunochemical identification of the 21.5K, 18.5K, 17K, 14K, and P2 proteins.

Animals↗

PubMedDate not supplied

Minocycline-associated tooth discoloration in young adults.

After observing a patient with adult-onset tooth discoloration coincident with minocycline administration, we retrospectively surveyed a cohort of patients with severe cystic acne during therapeutic trials with isotretinoin. Four of 72 patients who had minocycline therapy during adolescence were found to have minocycline-associated tooth discoloration, which occurred in one case after only four weeks of treatment. Thus, minocycline must be considered as an uncommon cause of tooth staining in adults.

Acne Vulgaris↗